Method and means for controlling kicks during operations in a borehole penetrating subsurface formations

ABSTRACT

In well drilling operations, a down-hole packer is carried by a drill string, above the drill bit, which is adapted to by inflated by use of drilling fluid under pressure when the drill bit is raised off the bottom. After the packer is set against the wall of the borehole, communication between the interior of the drill string and the well annulus is provided whereby a heavy drilling fluid may be pumped into the well displacing from the well a lighter drilling fluid, thereby providing a method for controlling pressure kicks during well drilling operations.

United States Patent Schuyf et al.

1451 Sept. 30, 1975 METHOD AND MEANS FOR CONTROLLING KICKS DURING OPERATIONS IN A BOREIIOLE PENETRATING SUBSURFACE FORMATIONS Inventors: Willem Schuyf, The Hague; Bart Tent, Rijswijk; Philip W. Pattynama, Rijswijk; Frans deKlerk, Rijswijk, all

of Netherlands Assignce: Shell Oil Company, Houston, Tex.

Filed: Dec. 6, 1973 Appl. No.: 410,589

Foreign Application Priority Data Jan. 4, 1973 United Kingdom 564/73 Sept. 10, 1973 United Kingdom 42472/73 US. Cl. 175/48; 166/184; 166/187;

Int. C1. EZlB 33/127 Field of Search 166/149, 150, 151, 185,

[56] References Cited UNITED STATES PATENTS 2,516,581 7/1950 Lynes et al. 166/150 X 3,236,307 2/1966 Brown 166/150 X 3,503.445 3/1970 Cochrum et al. 166/151 X 3,527,299 9/1970 Lewis 166/184 3,853,177 12/1974 Mott 166/184 X Primary E.\'mninerErnest R. Purser Assistant Erunziner-Richard E. Pavreau [57] ABSTRACT In well drilling operations, a down-hole packer is carried by a drill string, above the drill bit, which is adapted to by inflated by use of drilling fluid under pressure when the drill bit is raised off the bottom. After the packer is set against the wall of the borehole, communication between the interior of the drill string and the well annulus is provided whereby a heavy drilling fluid may be pumped into the well displacing from the well a lighter drilling fluid, thereby providing a method for controlling pressure kicks during well drilling operations.

29 Claims, 14 Drawing Figures US. Patent Sept. 30,1975 Sheet 1 of6 FIG. 7 Fl G. 2

U.S. Patent Sept. 30,1975 Sheet 2 of6 3,908,769

FIG. 3

\ r I v i 4 I 1 f i in 1 L l 1 J74 773 l H k T g X H5 770 o x Z o i i 723 XX -17? x:

m 1 F/G.4

U.S. Patent Sept. 30,1975 Sheet 3 of6 3,908,769

M102 FIG. 5

FIGS

US. Patent Sept. 30,1975 Sheet5 0f6 3,908,769

FIG. 77

FIG. 70

U.S. Patent Sept. 30,1975 Sheet 6 of6 3,98,769

FIG. 14

FIG. i3

METHOD AND MEANS FOR CONTROLLING KICKS DURING OPERATIONS IN A BOREHOLE PENETRATING SUBSURFACE FORMATIONS BACKGROUND OF THE INVENTION The invention relates to a method and means for controlling kicks during operations in a borehole penetrating subsurface formations.

During operations in a well, and in particular during drilling operations, there is a chance that notwithstanding the close control of the density of the mud which is applied i.a. for plastering the wall of the hole, an unbalance occurs between the pressure of the mud in the hole and the pressure of the fluid in the pore space of the subsurface formation through which or into which the borehole penetrates. This phenomenon is indicated as kick and can be detected by an increase in the return of mud from the borehole. Such increase of mud return results from fluid flowing out of the formation into the borehole and is due to the unbalance in pressures. If such kick is not controlled; and in particular if the fluid entering the borehole consists fully or partly of gas, the kick may easily lead to a blowout. As is known, a blowing well is extremely difflcult to control, and therefore all possible measures should be taken to prevent such a blow-out by controlling the kicks the moment they are noticed.

An object of the present invention is a means for con trolling kicks during operations in a borehole such as during drilling or during pulling of equipment from the hole, which means will allow kick control in a reliable and simple manner.

Another object of the present invention is a method for handling the means suitable for controlling kicks during operations in a borehole, which method allows a quick and safe suppression of kicks to prevent them for developing into blow-outs.

SUMMARY OF THE INVENTION According to the invention a. means for controlling kicks during operations in a borehole penetrating subsurface formations, which means is adapted to be included between two portions of tubular borehole equipment, comprises the following components:

an elongate body member with a conduit extending longitudinally therethrough, and a first valve system arranged in this conduit for controlling .the passage of fluid therethrough;

an inflatable packer around the body member and comprising an elastic annular element connected at each end thereof to an annular sleeve arrranged slidingly in axial direction on part of the outer wall of the elongate body member and sealing against the said outer wall, and i a second valve system to control fluid communication between the exterior of the body member and the conduit extending longitudinally through the body member and between the interior of the inflatable packer and the said conduit through the body member, said second valve system including one of the annular sleeves, means being provided for retaining said sleeve during inflation of the packer when supplying fluid to the interior thereof in a position in which it closes off the communication between-the exterior of the body member and the conduit through the body member but allows communication between this conduit and the interior of the inflatable packer. I

According to the invention, method for controlling kicks during opereations in a borehole penetrating subsurface formations in whichequipment is suspended including a drill string and the means according to the present invention, comprises the following steps:

a. stopping the operations;

b. closing off the annular space around the drill string at a level near the entrance of the borehole and actuating the first valve system to closing position;

c. pumping down fluid through the drill string to inflate the packer to close off the annular space around the drill string; A

d. stopping the pumping of fluid;

e. displacing the drill string with respect to the inflated packer set against the wall of the borehole, to operate the second valve system to open the communication between the exterior of the body member and the conduit extending through the body member;

f. opening the annular space at thelevel near the borehole entrance; I

g. resuming pumping of fluid through the drill string and changing the composition of this fluid;

h. displacing fluid in the annular space by the fluid of different composition;

i.,stopping the fluid circulation and subsequently displacing the drill string with respect to the inflated IBRIEF DESCRIPTION OF THE DRAWING The invention will now be described by way of example, with reference to two embodiments of the invention shown in the drawings. I

FIG. 1 of the drawings schematically shows a longitudinal section of a kick control means according to the invention;

FIG. 2 of the drawings schematically shows a longitudinal section of an alternative construction of the kick control means according to FIG.. 1;

FIGS. 38 of the drawings schematically show a longitudinal section of another construction of a kick control means according to the invention in various positions thereof;

FIG. 3 shows the control means during drilling of the hole;

FIG. 4 shows the control means just after a kick has been detected;

FIG. 5 shows the control means just before inflating the packer;

FIG. 6 shows the control means with the packer in the inflated position;

FIG. 7 shows the control means during circulation of a drilling mud with higher density than the original'drilling mud; and I FIG. 8 shows the control means during deflaction of the packer before rsuming drilling.

FIGS. 9l4 of the drawings schematically show part of a longitudinal section of still another embodiment of the invention in various positions thereof:-

FIG. 9 shows the control means during drilling of the hole;

FIG. 10 showsthe control meansjust after a kick has been detected;

FIG. 11 shows the control means just prior to inflating the packer;

FIG. 12 shows the control means during inflation of the packer;

FIG. 13 shows the control meansjust prior to circulation ofa drilling mud with higher density than the original drilling mud; and

FIG. 14 shows the control means just prior to deflation of the packer.

The kick control means shown in FIG. 1 comprises an elongate body member 1 having a central longtiudinally extending conduit 2 passing therethrough. The upper end of the body member 1 is provided with coupling means 3 for coupling the body member to (not shown) tubular equipment which is used for drilling a borehole. This equipment may include a drill string and a drill collar string connected to the drill string.

A packer 4 comprising two annular sleeves 5, 6 slidable arranged on the outer wall of the body member 1, is mounted around the body member 1 and adapted to be inflated to close off the annular space around the body member 1 when the latter issuspended in a borehole. This closing off can be performed by inflating the elastic annular element 7 which is connected at the ends thereof the annular sleeves and 6. Sleeve 5 slides over a part 8 of the body member 1 with diameter smaller than the diameter of the part 9 of the body member 1, which latter part is supporting the slidable annular sleeve 6. Since sleeve 5 is of larger crosssection than sleeve 6, sleeve 5 will always be forced upwards when the packer 4 is inflated by supplying pressure fluid via the bore 10 in the wall of the body member 1. Thus, communication via bore or port 10 between the interior of the packer 4 and the conduit 2 is maintained during inflation of the packer 4. During normal operations. the packer 4 rests with sleeve 6 thereof on shoulder 11 of the body member I. Inflation of the packer 4 moves the sleeve 6 upwards.

Once the packer 4 is inflated and the elastic element 7 thereof set against the wall of the borehole (not shown), the body member 1 can be displaced relatively to the packer 4. When lifting the body member 1, the packer 4 is maintained at the level at which it is set in the borehole. The bore 10 is moved past the sleeve 5 until it forms a communication between the exterior of the body member 1 and the conduit 2. Thus, sleeve 5 and bore 10 form a valve system which is indicated hereinafter as second valve system 12.

The lower end of the body member 1 carries a telescropic unit 13 comprising a key 14, a keyway 15 and a sleeve 16. The lower end of sleeve 16, although being shown in one piece with the drill bit 17, is normally formed separately thereof and coupling means are provided for connecting the sleeve 16 to the drill bit 17. Within the means of the present specification and claims, the bit 17 is understood to form part of the tubular equipment which can be suspended in a borehole. They key 14 and keyway 15 form torque transmission means to transmit the drilling torque from the body member 1 to the drill bit 17.

A first valve system is provided, which system comprises a first valve element 18 co-operating with a seat 19 and a second valve element 20 of the non-return type and co-operating with a seat 21 arranged on the lower of the body member 1. In its rest-position, valve element 20 is maintained at a predetermined distance from the seat 21 by valve cage 22 connected to the body member 1. Rod 23 passes through opening 24 in valve element 20 and connects the first valve element 18 to the sleeve 16 of the telescopic joint 13.

Openings 25 are arranged in the lower end of the sleeve 16 for passing the flow of drilling fluid from the interior of the sleeve 16 to the bit 17. These openings may be constituted by the nozzle openings of the drill bit 17.

The operation of the kick-control means shown in FIG. 1 is as follows.

During drilling, the kick control means shown in FIG. 1 is suspended in a borehole by tubular borehold equipment known per se, such as a drill string and drill collar string. The telescopic joint 13 and the packer 4 are then in the position shown in FIG. 1. Although there is a pressure difference between the fluid in the conduit 2 and the fluid in the space outside the body member 1, the elastic annular element 7 of the packer 4 is sufficiently stiff to withstand this pressure difference and to maintain a substantially annular form. The drilling fluid supplied from pumps at the surface (not shown) to the bit 17 passes through the conduit 2, between valve 18 and seat 19, between valve 20 and seat 21, and through the openings 25.

When a kick of dangerous magnitude is noticed in the drilling fluid system, these pumps supplying fluid to the conduit 2 are shut down and the drill string (not shown) to which body member 1 is attached, is lifted. The annular space around the drill string to closed off at the entrance of the borehole at the surface by blowout preventers known per se (not shown). The pressure in the borehole being higher than the pressure in the sleeve 16, the telescopic joint 13 remains in the retract position as shown. 1

By opening the upper end of the drill string to atmospheric pressure, fluid starts to flow from the hole through the openings 25 and past valve 20 and seat 21 into the conduit 2. This creates a pressure difference across valve 20 which consequently moves onto its seat 21 and closes off the entry to the conduit 2. When the flow ceases, the pressures inside and outside the sleeve 16 are the same and consequently the sleeve 16 moves downwards under influence of its own weight and the weight of the bit 17, thereby extending the telescopic joint 13. At the same time, the valve 18 is pulled into its seat 19. This valve stays in its seat when subsequently supplying fluid to the interior of the conduit 12 by starting the pumps. The pump pressure is then raised to a valve sufficient to inflate the packer 4 and to set the packer against the wall of the borehole. Sleeve 5 stays in its place during inflation and bore 10 remains open. Sleeve 6 is raised to a higher level. Since the packer 4 is clamped or forced against the wall of the borehole in frictional fluidtight engagement therewith, the drill string and the body member 1 can subsequently be raised with respect to the packer 4 to move the bore 10 of the second valve system 12 to an open position above the sleeve 5 of this valve system. The high pressure fluid then passes out of the conduit 2 through the bore 10 into the annular space above the inflated packer 4, and by opening the blow-out preventer means at the surface which closes the top of the annular space, a circulation of mud can be set up via the drill string and the annular space. By increasing the density of fluid which is circulated into this annular space thereby displacing the fluid of relatively lower density, the hydrostatic pressure above the packer 4 is increased. When this hydrostatic pressure is sufficiently high to control the kick pressure below the packer 4, circulation of fluid is stopped and the drill string is lowered to displace the bore to the position as shown in FIG. 1. Packer 4 is thereby deflated and further lowering of the drill string causes contraction of the telescopic joint 13 when the bit 17 is set on the bottom of the hole. Consequenly, the valve 18 is moved out of its seat 19 and drilling can be resumed. It will be appreciated that the kick control means is ready for use again.

Sealing means can be arranged where necessary to prevent flow of fluid between locations of different pressure. In particular, such sealing means are arranged between the sleeves 5 and 6 and the surfaces 8 and 9, respectively.

Valve 20 and valve 18 may be of shape different than shown in the drawings. The same applies for the seats 19 and 21. If desired, valve 20 may be omitted. The telescopic unit is then extended by lifting the drill string after closing the passage through the drill string and the passage through the annular space therearound at the entrance of the borehole.

By providing a channel (not shown) of small crosssection through the valve 18, the pressure prevailing below the inflated packer can be measured. This allows an exact calculation of the density of the fluid which is to be circulated into the borehole to control the kick. The kick control means in FIG. 2 does not comprise a telescopic joint as the tool shown in FIG. 1. This renders the tool cheaper and more reliable in the borehole. The body member 31 comprises a conduit 32 and a coupling 33 for coupling the member 31 to (not shown) tubular euqipment for carrying out operations in a hole. Since the body member 31 carries a drill bit 34, these operations are drilling operations and the tubular equipment is a drill string. Suitable coupling means (not shown) are arranged between the lower end of the body member 31 and the drill bit 34. As in Fig. 1, the tool shown in Flg. 2 has a packer 35 comprising two annular sleeves 36, 37 slidably over the outer wall of the member 31, and an inflatable elastic annular element 38. The sleeve 36 has a cross-section larger than the cross-section of the sleeve 37 and is carried by a part 39 of the member 31 which has a crosssecion smaller than the cross-section of the part 40 of the body member 31. The lower sleeve 36 is carried by a shoulder 41 of the member 31 and the elastic annular element 38 is sufficiently stiff to maintain the packer 35 in the position shown.

A first valve system 42 and a second valve system 43 are carried by the body member 31.

The second valve system 43 comprises three elements, to wit the sleeve 36, a bore 44 and an inner sleeve 45, which sleeve is carried via a rod 46 by the first valve system 42.

The first valve element of the first valve system 42 is formed by a non-return valve 47 and has a dampening system connected thereto. The dampening system consists of an oil-filled cylinder 48 and a piston 49 connected to the valve element 47. A small diameter bore 50 is arranged through the piston 49. The lower end of the valve element 47 has an opening 51 ofa size to create a pressure difference across the valve element 47 when there is an upward flow of fluid through this opening, which difference is sufficiently great to move the valve element 47 upwards against the action of a spring 53 to close around the lower end of the second valve element 54 of the first valve system 42. This latter valve element is connected via rod 46 to the inner sleeve 45 of the second valve system 43.

The opening 51 communicates via space 52 with opening 53A in the lower end of the body member 31. This opening 53A may also be formed by the jet nozzle or jet nozzle of the drill bit 34.

When the tool shown in FIG. 2 is suspended in a borehole from tubular borehole equipment, there is an unobstructed passage for drilling fluid supplied by pumps (not shown) via the drill string and drill collar string to the body member 31, through which the fluid passes along the conduit 32, the interior of sleeve 45, the space around the second valve element 54, the passage between the first valve element 47 and the second valve element 54, the interior of the first valve element 47, the opening 51, space 52 and opening 53A to the drill bit 34.

When a kick occurs in the borehole, the pumps are shut down by. an operator and a blow-out preventer (not shown) is actuated to close off the annular space around the drill string at the entrance of the borehole. Thereafter the upper end of the drill string is opened which results in an upward flow of fluid through the opening 53A, the space 52, the opening 51 and the interior 55 of valve element 47. This flow creates a presssure difference across the valve element 47 which subsequently moves upwards and closes around the valve element 54. The speed at which the valve element 47 moves is i.a. controlled by the dampening means 48, 49 and 50.

Subsequently, the pumps are restarted and the pressure in conduit 32 is raised which results in a downward movement of the first valve system 42. The spring 53 tries to urge the first valve element 47 and the second valve element 54 apart during this downward movement, but is counteracted by the dampening means 48, 49 and 50, so that the valve element 54 remains in sealing contact with the valve element 47 until the latter is again in the position shown in FIG. 2. The pump pressure above the first valve system 42 being higher than the kick pressure in the hole, the valve elements 54 and 47 remain in contact and close off the passabe through the conduit v32.

The downward displacement of valve 54 effects the operation ofthe second valve system 43 by the displacement of the inner sleeve 45 therby uncovering bore 44. Bore 44 then forms a communication betweeen conduit 32 and the interior of packer 35 which results in inflation of the packer by the high pressure fluid entering the bore 44. Once the packer 35 is set against the (not shown) wall of the borehole, the drill string is lifted to expose the bore 44 to the annular space above the packer 35. The high pressure fluid then flows into this annular space and by opening the blow-out prevent at the entrance of the borehole, the fluid in this annular space can be displaced by a fluid with higher density than the fluid originally present in this annular space. This high density fluid is supplied by the (not shown) pumps to the interior of the drill string. When the hydrostatic pressure above the packer 35 has been raised to a sufficient extend, the drill string is lowered again to bring the bore 44 into communication with the interior of the packer 35 and with the conduit 32. By gradually lowering the pressure of the fluid in the conduit 32, the packer is deflated, and when the pressure above the closed first valve system 42 equals the pressure in the borehole, the two valve elements 47 and 54 of this valve system 42 separate under influence of the spring 53 and the free passage through the conduit 32 is restored, whereafter the operations which were being carried out in the borehole prior to the occurrence of the kick, can be resumed.

If desired, a vent conduit can be incorporated in the second valve system 43, to vent the interior of the packer 35 in the position of the inner sleeve as shown in FIG. 2 to the exterior of the body member 31 at a location above the packer.

During operation of the kickcontrol means shown in FIG. 2 to control a kick in the manner as herein described above, the pressure of the kick can be measured in the inflated position of the packer. Thcreto, after the drill string has been lifted to displace bore 44 to a position above the annular sleeve 36, the pressure within the conduit 32 is gradually lowered until a constant pressure is reached. This pressure is the kick pressure and starting herefrom the required density of the fluid which is to be circulated into the annular space above the packer to control the kick can be calculated.

The first valve system 42 has been opened by this gradual pressure decrease in the conduit 32. To close this valve system again (as is necessary to allow circulation of the fluid to displace the relatively low density fluid in the annular space above the packer) the drill string is opened at its upper end to an extend sufficient to create an upward flow in the conduit 32 which flow displaces the first valve element 47 of the first valve system 42 upwards to close against the second valve element 54 of this system. Thereafter the pressure in the conduit 32 is raised quickly to displace the first valve system 42 downwards without allowing the elements 47 and 54 to be separated under influence of the spring 53. Thereby, the bore 44 is brought again into communication with the conduit 32 and the circulating step as described already hereinabove can be carried out.

Instead of a single bore 44 as shown in FIG. 2, two bores may be applied. the first bore forming a communication between the conduit 32 and the annular space above the packer 35 when inflated. and the second bore forming a communication between the conduit 32 and the interior of the packer 35. The sleeve 36 in its upper end position closes off the second bore and in its lower end position closes off the first bore. The inner sleeve 45 cooperates with the second bore only.

The dampening means which control the speed at which the first valve element 47 of the first valve system 42 can be displaced may also be arranged between the first valve element 47 and the second valve element 54 of the first valve system 42. These dampening means need to function only when the first valve system 42 is moving downwards. Thus, a channel (not shown) of larger cross-section than the bore 50 in the piston 49 of the dampening means may be applied to interconnect the two portions of the cylinder 48. A non-return valve (not shown). which operates only to close this channel when the first valve system 42 moves downwards is incorported in this channel.

To lock the second valve element 54 of the first valve system 42 in the closed position. a cylinder/piston sys tem (not shown) may be arranged between this valve element or an extension thereof and the body member 31. The cylinder communicates by a bore (not shown) with the space below the packer 35 when inflate, the entrance to which bore is controlled by the position of the annular sleeve 37. By manipulating the drill string with respect to the inflated packer, the fluid within the cylinder can be locked up, thus locking the second valve element 54 in the closed position thereof.

A similar locking system as describe in the preceding paragraph may be applied to the first valve element 47 of the first valve system 42. The cylinder of such locking system (not shown) may assist in closing the first valve element 47, which means that the cross-section of the bore 51 can be enlarged. This cross-section may even be made equal to the cross-section of the passage 52. This type of locking system is also hereinafter described with reference to the embodiment shown in FIG. 9.

The sleeves of the packers 4 and 35 shown in the drawing both comprise sealing element to maintain the pressure at which the packers are inflated, when-the drill string is displaced with respect to the packers and the communication between the conduits extending longitudinally through the body members and the packer interior is closed off.

When the tool as shown in FIG. 2 has two bores instead ofa single bore 44 (the operation of this two-bore system being explained above) and further has a cylinder/piston locking arrangement cooperating with the first valve element 47 of the valve system 42 (as also explained hereinabove), the packer will have to cooperate with the body member via a pin and slot system allowing the packer when inflated to be positioned in three distinct positions with respect to the body memher, the annular sleeve forming part of the second valve system closing off the communication between the exterior of the body member and the conduit extending through the body member in the first position and second position, said sleeve closing off the communication between the said conduit and the interior of thepacker in the second and third position, and the other sleeve closing off the entrance to the bore leading from the exterior of the body member to the cylinder/piston system of the first valve element of the first valve system in the third position.

The construction and operation of the kick control means shown in FIGS. 3-8 of the drawings will now be described.

It will be appreciated that the kick control means shown in FIGS. 3-8 is mounted at a suitable location in tubular euqipment used for drilling a hole in the subsurface of the earth and that the upper part of the elongate body member 101, as well as the lower part of this body member. is provided with means (not shown) for coupling the body member to the tubular equipment. This equipment may include a drill string and a drill collar string connected to the drill string.

The elongate body member 101 (see FIG. 3) comprises a longitudinally extending conduit 102 passing therethrough.

A packer 104 comprising two annular sleeves 105, 106 slidably arranged on the outer wall of the body member 101, is mounted around the body member 101 and adapted to be inflated to close off the annular space around the body member 101 when the latter is suspended in a borehole. This closing off can be performed by inflating the elastic annular element 107 which is connected at the ends thereof to the annular sleeves and 106. Sleeve 105 is adapted to slide over a part 108 of the body member 101. with diameter smaller than the diameter of the part 109 of the body member 101, which part is supporting the slidable annular sleeve 106. Since sleeve 105 has a cross-sectional area larger than the cross-sectional area of sleeve 106, sleeve 105 will always be forced upwards during inflation of the packer 104 when pressure fluid is supplied via the bore 110 in the wall of the body member 101. Thus, communication between the bore 110 and the interior of thepacker 104 is maintained during inflation of the packer 104. During normal operations, the packer 104 rests with sleeve 1'06 thereof on shoulder 111 of the body member 101. Inflation of the'paeker 104 moves the sleeve 106 upwards.

A first valve system 112 and a second valve system 113 are carried by the body member 101.

The second valve system 113 comprises three elements, to wit the sleeve 105, the bore 110 and a valve 114, which valve is carried via a rod 115 by the first valve system 112, as will be explained hereinafter. The valve 114 can be displaced between two end positions. In the upper end position, the valve 114 rests against the shoulder 116 of the valve housing 117 forming part of the body member.101. In the lower end position, the valve 114 rests against the shoulder 118 of the valve housing 117. A spring 119 resting at one end thereof against the guide 120 for the rod 115, urges the valve 114 to the upper end position. Guide 120 forms part of the valve housing 117.

The annular space 121 between the two parts 114 A and 114 B of the valve 114 communicates in the upper end position of the valve 114 with the interior of the packer 104 via the bore 110 and with the exterior of the body member 101 via a conduit 121 A. In the lower end position of the valve 114, which position is shown in FIG. of the drawings, the interior of the packer 104 communicates with the conduit 102 via the bore 110, whereas the exterior of the body member 101 remains in communications with the annular space 121 of the value 114 via the conduit 121A.

The lower end of the rod 115 is connected to the first valve system 112. This first valve system 112 comprises a first valve element 112 and a second valve element 123 which latter element is connected to rod 115. The first valve element 122 is movably arranged between two end positions. In the lower end postiion (shown in FIG. 3 of the drawings) this valve element 112 rests on the shoulder 124 arranged on the inner wall of the conduit 102 of the body member 101. In the upper end position (shown in FIG. 4) the -first valve element 122 rests against the shoulder 125 formed on the housing 117 of the second valve system 113.

A spring 126 urges the first valve element 122 of the first valve system 112 to its lower end position. This spring is arranged in an oilfilled cylinder 127 which forms a dampening system together with the piston 128 mounted on the first valve element 122. The piston has one or more small diameter bores 129' passing therethrough.

Further, a cylinder/piston system is arranged on the first valve element 122 of the first valve system 112, which cylinder/piston arrangement consists of a cylinder 130 and a piston 131. The cylinder 130 communicates via a bore 132 with the interior 133 of the packer 104.

The first valve element 122 of the first valve system 112 has a central passage 134 passing therethrough.

10 This first valve element 122 is of the non-return type and can beclosed by reversing'the flow in a direction opposite to the arrows (which indicate the way of the drilling fluid during drilling operations). This reversed flow will create a pressure difference over the jet nozzles (notshown) of the drill bit (not shown). Since the cylinder space 130 below the piston 131 communicates via the bore 132, the interior 133 of the -packer 104, the bore 110, the space 121 and the conduit 121A with the exterior of the body member 101, this pressure difference will also exist over the piston 131 and the force resulting therefrom will displace the valve 122 to a position in which this valve 122 is in contact with valve 123. This displacement of the valve 122 to closing position is enhanced by the pressure'difference created by the flow over the valve element '122 when passing through the passage 134 of this valve element.

The first valve element 122 of the first valve system 112 is adapted to cooperate with the second valve element 123 of the same system to close off the passage through the conduit 102 in the position shown in FIG. 4 of the drawings. Suitable sealing means (not shown) are arranged between the parts of the valve elements 122 and 123 contacting each other.

The relative position between the valve elements 122 and 123 can be maintained (as will be explained hereinafter) during the displacement of these elements forming the first valve system 112 to a position in which the first element 122 is inits lower end position (see FIG. 5).

Sealing means can be arranged when necessary to prevent flow of'fluid between locations of different pressure. In particular, sealing means may be arranged between the sleeves and 106 and the surfaces 108 and 109, respectively.

The operation of the kick control means as shown in FIGS. 3-8 of the drawings is as follows.

When the tool is suspended in a borehole in the position shown in FIG. 3, there is an unobstructed passage for drilling fluid supplied by (not shown) pumps via the drill string the drill collar string (not shown) to the body member 101 through which the fluid passes via the conduit 102, therby passing along the side wall of the valve housing 117, through the space between the first and second elements 122 and 123 of the first valve system 112 and through the central passage 134 of the valve element 122. Subsequently, the flow (the direction of which is indicated by arrows) passes through suitable tubular equipment (not shown) to a drill bit (not shown).

When a kick occurs in the borehole, the pumps are shut down and a (not shown) blow-out preventer is actuated to close off the'annular space around the drill string at the entrance of the borehole. Thereafter, the upper end of the drill string is opened which results in an upward flow of fluid (in a direction opposite to the direction indicated by the arrows in FIG. 3) through the conduit 102. This flow which results from the relatively high kick pressure in the hole creates a pressure difference across the valve element 122 and the piston 131 thereof, which valve element 122 subsequently moves upwards and closes around the valve element 123. This position is shown in FIG. 4. The speed at which the valve element 122 moves is. inter alia, controlled by the dampening means 127l29.

subsequently, the pumps ae restarted and the pressure in conduit 102 is raised which results in a downward movement of the first valve system 112 (see FIG. The spring 126 tries to urge the first valve element 122 and the second valve element 123 apart during this downward movement. but is counteracted by the dampening means 127-129, so that the valve element 122 remains in sealing contact with the valve element 123 until the first is in its lower position shown in FIG. 5. The pump pressure above the first valve system 112 being higher than the kick pressure in the hole, the valve elements 122 and 123 remain in contact and close off the passage through the conduit 102.

The downward displacement of valve 123 effects the operation of the second valve system 113 by the displacement of the valve 114 which is connected to the valve element 123 of the first valve system 112 via the rod 115. The entrance to the bore 110 is then opened (see FIG. 5) and pressure fluid at a pressure higher than the kick pressure in the hole can then enter the space 133 of the packer 104 and the cylinder 130 below the piston 131 mounted on the valve element 122 of the first valve system 112 (see arrows in FIG. 5). This results in inflation of the packer 104, whereby the packer is pressed into sealing contact with the (not shown) Wall of the borehole. Once the packer 104 has been inflated (see FIG. 6) and set against the wall of the borehole, the drill string is lifted to move the body member 101 relatively to the packer clamped against the wall so as to expose the bore 110 to the annular space above the packer 104 (see FIG. 7). The pump is subsequently stopped.

During the displacement of the body member 101 relative to the packer 104 set against the wall of the borehole, the fluid present in the space 133 of the packer 104 is first closed off from the conduit 102 and subsequently further compressed by the displacement of the annular sleeve 105 (which has a relatively large cross-section compared to the sleeve 106) towards the annular shoulder 135 between the parts 108 and 109 of the body member 101, over which parts the annular sleeves 105 and 106 are displaced. The pressure in the space 133 is thus increased to a value higher than the pressure in the conduit 102 at the level of the packer 104, which results in upward displacement of the valve member 122 of the first valve system 112. During this latter operation. the packer 104 remains in sealing contact with the wall of the borehole and with the body member 101.

The difference in volume of the cylinder space 130 in the position of valve element 122 shown in FIG. 6 and in the position of this valve element 122 shown in FIG. 7 equals the difference in volume of the space 133 ofthe packer 104 in these two positions. In the embodiment as described here. the sleeve 105 contacts the shoulder 135 at the end of the stroke. whereas the same time the valve element 122 contacts shoulder 125 of the valve housing 117.

After the valve element 122 has been displaced to the position shown in FIG. 7. the pressure of the kick (that a is the pressure of the fluid in the annular space around the drill string but below the inflated packer 104) can be measured as follows.

In the position shown in FIG. 7. the upper end of the annular space above the packer 104 is still closed off. If this annular space contains liquid only and the entrance to the drill string is closed off prior to stopping the pump. the pressure prevailing in conduit 102 just above the valve system 112 will be higher than the kick pressure prevailing in the conduit 102 but below the valve system 112. By gradually lowering the pressure in the conduit 102 above the valve system 112 (e.g.. by a controlled blowing off the pressure at the top of the drill string) a situation will be reached at which the pressures above and below the valve system 112 are substantially equal, which will result in an upward movement of the combination of the valve 114 and the valve element 123. which combination then acts as a measuring piston. This upward movement is haltered by the valve 114A when contacting the shoulder 116. Then the communication between the conduit 102 and the bore (which latter in the position shown in FIG. 7 communicates with the annular borehole space above the packer 104) will be closed. The pressure then measured at the top of the drill string is equal to the kick pressure minus the pressure created by the hydrostatic column in the drill string and by the spring 119. The moment at which the valve 114 closes off the entrance to bore 110 can be detected by observing the pressure decline in the annular borehole space above the packer 104.

However. if the annular space above the packer 104 contains a fluid partly consisting of gas, kick pressure measurement will have to be performed in another manner than described above. It will be appreciated that in this case. when the string is displaced to bring the bore 110 into communication with the annular space above the packer 104 and the pump is stopped, the pressure in the drill string will fall below the kick pressure due to the compressibility of the gas present in the annular space above the packer 104. Consequently the valve 114 will be moved upwards to the position as shown in FIG. 4 under influence of the kick pressure acting on the lower end of the valve element 123. The communication between the bore 110 and the conduit 102 is broken in this position of the valve 114. Subsequently the pressure in the drill string is gradually increased by a controlled supply of pressure liquid at the entrance of the drill string. At the same time the behaviour of the pressure in the annular space above the packer 104 is observed. When the pressure inside the drill string has risen to a value at which the pressure just above the valve 114 is slightly greater than the sum of the kick pressure below the valve element 123 and the pressure exerted by the spring 119. the valve 114 will be moved downwards. therby opening the entrance to the bore 110. This movement can be ascertained by observing the pressure in the annular space above the packer 104, which pressure will then start to rise. The pressure measured at that particular moment at the to of the drill string is then equal to the kick pressure minus the pressure created by the hydrostatic column in the drill string and by the spring 119.

It will be appreciated that during the above-described pressure measuring steps, the space below the packer I04 remains isolated from the rest of the hole as well as from the interior of the drill string, thus preventing the entrance of any high pressure fluid into the hole or the drill string. In particular. the entrance of high pressure gas. which would hamper the exact measuring of the kick pressure. is prevented. This isolation of the kick Zone from the rest of the hole is obtained by the action of the valve element 123 and the valve 114, which combination acts as a measuring piston.

It will be understood that. if desired, the pressure variation performed at the top of the drill string to measure the kick pressure, may be carried out more than once. Thus, the pressure at the entrance may first be decreased to a value at which the valve 114 moves upwards, and subsequently be increased to a value at which this valve 114 moves downwards. Also this pressure may first be increased and subsequently be decreased.

To be absolutely sure that no gas is present either in the drill string, or in the annular space above the packer 104, the fluid present in these spaces may be circulated out by a liquid. This circulation may be in the direction of the arrows shown in'FIG. 7, or in the direction opposite thereto.

By measuring the pressure as described above, the kick pressure can be calculated and a mud with specific density sufficient to control the kick is then prepared. Subsequently, this mud is circulated into the drill string at a pressure sufficient to move the valve 114 and valve element 123 downwards against the kick pressure and the action of spring 119 so as to open the entrance to bore 110 (see FIG. 7) and thus allowing the mud with relatively low density as present in the drill string and the annular borehole space above the packer 104 to be replaced by the heavier mud. To allow such circulation, the upper end of the annular borehole space is opened and the mud pumps are started to pump the new mud down through the drill string.

When the annular borehole space is filled with mud having a relatively high density, the circulation of mud is stopped and the drill string is moved relatively to the packer 104 set against the wall of the borehold. Consequently, the valve 114 moves upwards thereby bringing one side of the bore 110 into communication with the conduit 121A. Further, the other side of the bore 110 is brought into communication with the interior 133 of the packer 104. This position is shown in FIG. 8 and the arrows indicate the flow of liquid out of the cylinder spacer 130 and the interior 133 of the packer 104. Consequently, the valve member 122 moves downwards thereby reopening the passage through conduit 102, and the packer is deflated and under influence of its elasticity obtains the original position thereof as shown in FIG. 3.

Drilling operation can now be resumed by pumping the mud with relatively high density down through the drill string and by rotating the drill string.

It will be appreciated that since the packer 104 can be placed just above the drill bit (not shown), the present tool allows a replacement of substantially the total amount of mud present in a borehole that is being drilled.

By lifting the drill string, the packer 104 can be set at any desired level in the hole, which allows setting of the packer against competent parts of the wall of the borehole.

During normal operations carried out by tubular equipment in which the present tool is incorporated, the packer 104 cannot be inflated inadvertently, since inflation of the packer requires first a reverse liquid flow in the tubular equipment.

If desired, a spring (not shown) may be inserted between the sleeve 106 and the shoulder 111. This results in an available stroke length for sleeve 106 sufficiently large to allow opening of bore 110 to the exterior space of the body member 101 when displacing the string with respect to the inflated packer, even if this packer is set against the wall of a hole having a diameter only slightly greater than the outer diameter of the body member 101.

It is further remarked that in the position of the packer 104 and the valve element 122 as shown in FIG. 7, the sleeve 105 and the valve element 122 need not necessarily be in contact with the shoulders 135 and 125 respectively. It will be sufficient if only one of the shoulders is contacted by the cooperating member. However, the valve element 122 should have been raised sufficiently to remain in sealing contact with the valve element 123 when the latter is raised to its upper end position (vide relative position of valve element 122 and 123 shown in FIG. 4).

The kick control means can also be operated to control kicks that occur during operations in the borehole other than drilling. Such other operations may include pulling of equipment out of the well.

Since the dampening means need to function only when the first valve system 112 is moving downwards, a channel (not shown) of larger cross-section than the bores 129 in the piston 128 of the dampening means may be applied to interconnect the two parts of the cylinder 127. A nonreturn valve (not shown which operates only to close this channel when the first valve ele ment 122 moves downwards, is incorporated in this channel.

The construction and operation of the kick control means shown in FIGS. 9-14 of the drawings will now be described.

The main difference between the embodiments of the invention shown in FIG. 9 and FIG. 3 resides in the locking system that is used for locking the first valve element of the first valve system in the upper position thereof. A further difference is the position of the opening for draining mud from the inflatable packer during deflation thereof. This opening is positioned near the lower end of the packer and thus obviates collection of solids settled out of the mud in the lower part of the packer interior.

Just as the kick control means according to FIG. 3, the kick control means according to FIG. 9 is mounted at a suitable location in tubular drilling equipment used for drilling a hole. Thereto, the upper and lower ends of the elongated body member 201 comprise screw couplings (not shown) for coupling the body member 201 to the tubular equipment.

The body member 201 comprises an axially extending conduit 202. Further, a packer 204 is slidingly mounted on the outer wall of the body member 201, this packer comprising two annular sleeves 205 and 206, and an elastic annular element 207 connected thereto. The outer surface of the body member 201 comprises a stop member 208 for limiting the downward stroke of the sleeve 205. The right surface 209 of the body member 201 limits the upward stroke of this sleeve 205. A spring 210 is arranged below the sleeve 206 to keep the packer 204 in the position shown in FIG. 9 when deflated and in the position shown in FIG. 12 when inflated. In both positions. the bore 211 is closed off by the sleeve 205 from communication with the space outside the body member 201.

In the deflated position of the packer 204 as shown in FIG. 9, the interior 212 of the packer communicates via bore 213, space 214 and bore 215 with the exterior of the body 201. This bore 215 is closed off by the sleeve 206 from communication with the exterior of the body 201 when the body 201 is lifted with respect to the inflated packer 204 to the position shown in FIG. 13 of the drawings.

Two valve systems are arranged inside the passage 202 through the body member 201. The first valve system 216 comprises the sleeve valve 217 and the valve body 218. The upper part of the sleeve valve 217 (which is a non-return valve) can cooperate with the valve body 218. This valve body 218 is connected to the ring valve 219 A of the second valve system 219. The sleeve 205 and the bore 211 form part of the second valve system 219. During drilling, the right valve 219A of the second valve system 219 is kept in the position shown in FIG. 9 by the action of the spring 220, whereas the sleeve valve 217 of the first valve system 216 is maintained in its lower position by the action of the spring 221. The spring 221 is mounted in an oilfilled dampening chamber 222 comprising a piston 223 with bore 224.

The sleeve valve 217 comprises three more pistons 225, 226 and 227. Piston 225 cooperates with a cylinder space 228 that communicates with the axially ex tending conduit 202 via a bore 229. The bore 229 is closed off in the position shown in FIG. 12 of the first and second valve systems 216 and 219 thereby trapping liquid in the cylinder space 228 and preventing downward movement of the sleeve valve 217. Piston 226 closes off the cylinder space 214 at the upper end thereof. When supplying a high-pressure liquid to the space 214, the sleeve value 217 moves upwards to the position shown in FIG. 10 under influence of this pres sure which operates on the piston 226 in the beginning of the stroke. and on piston 227 at the end of the stroke.

In the position of valve 218 as shown in FIG. 13, the sleeve valve 217 is locked in its upper position by the liquid pressure exerted in the cylinder space 234 as will be explained hereinafter.

In all positions of the sleeve valve 217, the space 230 (see FIG. 9) above the piston 226 is vented via the bore 231.

The operation of the kick control as shown in FIGS. 914 of the drawings is as follows.

The position of the first and second valve systems 216 and 219 during normal drilling is shown in FIG. 9. The flow of drilling fluid is indicated by the arrows 232. The pressure of the drilling fluid passing through the central conduit 202 acts (via the bore 231) on the upper side of the piston 226 of the valve sleeve 217 of the first valve system 216. Since this pressure is larger than the pressure outside the body 201, which pressure .inter alia acts (via the bore 215) on the lower side of the piston 226, the sleeve valve 217 remains in the lower position thereof as shown in FIG. 9.

When a kick occurs, the blow-out preventers on top of the hole are closed and the supply of drilling liquid to the conduit 202 is shut down by the drilling operator. By opening the top of the drill string to atmospheric pressure, the pressure above the piston 226 drops below the pressure outside the body member 201 (and acting below the piston 226). As a result thereof, the sleeve valve 217 is moved upwards to the position shown in FIG. 10, thereby compressing spring 221. The upper end of the sleeve valve 217 closes around the valve body 218 thereby closing off the passage through the axial conduit 202.

Thereafter the supply of liquid to the drill string is resumed and the pressure above the valve body 218 is increased to displace the valve body 218 downwards (see FIG. 11) against the action of the spring 220, thereby also displacing ring valve 219A of the second valve system and opening the bore 211 to allow pressure fluid to flow out of conduit 202 (see arrows 233 in FIG. 12) to the interior 212 of the packer 204, thereby inflating the elastic annular member 207 to press this member against the wall of the bore hole (not shown). The sleeve valve 217 is prevented from downward movement by the action of the dampening means 221-224 and subsequently remains in its upper position since the bore 229 is closed off by the valve body 218 thereby trapping the liquid in the cylinder space 228. During inflation of the packer 204, the lower sleeve 206 of the packer is displaced upwards by the spring 210. The sleeve 205 of the packer 204 remains in its upper position, and the bore 211 remains open for the supply of liquid to the interior 212 of the packer 204.

Subsequently, the supply of liquid to the passage 202 is stopped, which results in a drop of pressure in the space above the valve body 218, which body then moves upwards together with the ring valve 219A thereby closing off the bore 211 (see FIG. 13). Thereafter, the drill string in which the kick control means of FIGS. 944 is mounted is lifted and the body member 201 is displaced upwards (see FIG. 13) with respect to the packer 204 which is clamped against the (not shown) wall of the bore hole. As a result of this displacement, the bore 211 which used to communicate with the interior 212 of the packer 204, is now brought into communication with the exterior of the bore hole above the packer 204, whereas the bore 215 which used to communicate with the exterior of the body 201, is brought into communication with the interior 212 of the packer 204.

Subsequently, by increasing the pressure above the valve body 218, this body will be displaced downwards together with the ring valve 219A of the second valve system (this position of ring valve 219A is not shown in FIG. 13). The bore 211 is thereby uncovered and pressure fluid is allowed to flow from the space above the valve body 218 to the space above the packer 204 in the bore-hole. As explained already in detail with reference to the embodiment shown in FIGS. 38, the pressure fluid may be of a relatively large density to displace fluid of relative low density in the annular space of the bore-hole. Also. the pressure prevailing below the valve body 218 can be measured to get information on the kick pressure. This pressure measurement can be carried out in the same manner as explained with reference to the embodiment shown in FIG. 7 of the drawings.

It will be appreciated that during all the operations carried out during pressure measuring and during circulation of drilling fluid through the bore 211, the sleeve'valve 217 will remain in its upper position since downward movement thereof is prohibited by the liquid trapped below the piston 227. Though this liquid is via bore 215 in communication with the interior 212 of the packer 204, this liquid cannot escape from space 234 as the packer 204 cannot be further inflated.

After a sufficient amount of fluid has been transferred from the conduit 202 to the annular space above the packer 204, the pump supplying this liquid is stopped. The pressure in conduit 202 above the valve 218 is lowered and the valve body 218 together with ring valve 219A moves upwards thereby closing off the bore 211 (see position shown in FIG. 13).

Thereafter, the body member 201 is lowered (see FIG. 14) with respect to the inflated packer 204 by lowering the drill string (not shown) until the ring surface 209 of the body member 201 contacts the sleeve 205. The bore 215 is uncovered by this displacement and the liquid can escape from the cylindrical space 234 to the exterior of the body member 201 under influence of the displacement of sleeve valve 217 which is moved downwards by the action of spring 221. The liquid in dampening chamber 222 is then displaced through the port 224. In the lower position of the sleeve valve 217 (which position is the same position as shown in FIG. 9) the interior 212 of packer 204 communicates via the bore 213 and the space 214 with the bore 215 and the drilling fluid present in the packer 204 is dispelled therefrom under influence of the elasticity'of the annular member 207. Any solids that have settled out in the lower part of the interior 212 of the packer 204 are removed by the liquid flowing out of the packer. The packer in its deflated position is ready for use again and drilling can be resumed with the packer 204 and the two valve systems 216 and 219 in the position shown in FIG. 9.

It will be appreciated that sealing members (such as O-seals) may be provided .on the surfaces that are used for sealing contact with other elements of the kick control means.

Further, the annular sleeves 205 and 206 may show the same difference in diameter as shown by the annular sleeves 105 and 106 of the embodiment according to FIG. 3 of the drawings.

We claim as our invention:

1. Means for controlling kicks during operations in a bore hole penetrating subsurface formations, said means being adapted to be included between two portions of tubular bore hole equipment and comprising:

an elongated body member with a conduit longitudinally therethrough, and a first valve system arranged in this conduit for controlling the passage of fluid therethrough;

an inflatable packer around the body member and comprising an elastic annular element connected at each end thereof to an annular sleeve arranged slidingly in axial direction on part of the outer wall of the elongate body member and sealing against the said outer wall; and

a second valve system to control fluid communication between the exterior of the body member and the conduit extending longitudinally through the body member and between the interior of the inflatable packer and the said conduit through the body member, said second valve system including one of the annular sleeves, means being provided for retaining said sleeve during inflation of the packer when supplying fluid to the interior thereof in a position in which it closes off the communication between the exterior of the body member and the conduit through the body member but allows communication between this conduit and the interior of the inflatable packer.

2. Means according to claim 1, wherein the annular sleeve forming part of the second valve system has a cross-section greater than the crosssection of the other annular sleeve, and is mounted on part of the body member having a smaller cross-section than the part on which the other annular sleeve is mounted.

3. Means according to claim 1, wherein the annular sleeves of the packer are freely rotatable around the body member. v

4. Means accordingto claim 1, wherein the annular sleeve forming part of the second valve system is movable between two end positions and cooperates with at least one bore in the wall of the body member, which interior of the packer in the second and third position, and the other sleeve closing off the entrance to the bore leading from the exterior of the body member to the cylinder/piston system of the first valve element of the first valve system in the third position.

5. Means according to claim 4, wherein the second valve system includes fluid control means arranged in the conduit through the body member and actuatable by the first valve system, these fluid control means being displaceable between two end positions and closing off the bore in one of the end positions.

6. Means according to claim 5, wherein a vent conduit is provided to vent the interior of the packer to the exterior of the body member in one of the end positions of the sleeve and of the fluid control means of the second valve system.

7. Means according to claim 5, wherein the first valve system comprises a first valve element and a second valve element, each element being movable-between two end positions, means adapted to urge the valve elements apart to positions in which there is a free passage through the conduit extending longitudinally through the elongated body member, and dampening means adapted to control the relative speed between the elements when they are urged apart, the two valve elements when contacting each other closing off the passage through the said conduit, the first valve element being a non-return valve and the second'valve element being coupled to the fluid control means of the second valve system.

8. Means according to claim 7, wherein the dampening means operate only when the valve elements of the first valve system are moved in the direction of the flow of drilling liquid when passing through the tubular borehole equipment.

9. Means according to claim 7, wherein the dampening means is of the hydraulic type and arranged be tween the two valve elements ofthe first valve system.

10. Means according to claim 7, wherein the dampening means is of the hydraulic type and arranged between the first valve element of the first valve system and the body member.

11. Means according to claim 7, wherein a cylinder/- piston system is arranged between the second valve element of the first valve system and the body member, said cylinder communicating with the exterior of the body member via a bore in the wall of the body memher, which bore can be closed off by that annular sleeve of the inflatable packer, which sleeve does not form part of the second valve system.

12. Means according to claim 7, wherein a cylinder/- piston system is arranged between the first valve element of the first valve system and the body member, said cylinder communicating with the interior of the inflatable packer.

13; Means according to claim 7, wherein a cylinder/- piston system is arranged between the first valve element of the first valve system and the body member,

said cylinder communicating with the exterior of the body member via a bore in the wall of the body member.

14. Means according to claim 13, wherein the packer cooperates with the body member via a pin and slot sys tem allowing the packer when inflated to be positioned in three distinct positions with respect to the body member, the annular sleeve forming part of the second valve system closing off the communication between the exterior of the body member and the conduit extending through the body member in the first position and second position, said sleeve closing off the communication between the said conduit and the bore in one end position of the sleeve forms a communication between the conduit through the body member and the exterior of the body member, and in the other end position of the sleeve forms a communication between the conduit through the body member and the interior of the inflatable packer.

15. Means according to claim 7, wherein a cylinder/- piston system is arranged between the first valve element of the first valve system and the body member, said cylinder communicating with the conduit extending axially through the body member via a bore, the entrance to which bore being controlled by the fluid control means of the second valve element that are arranged in the conduit.

16. Means according to claim 15, wherein a second cylinder/piston system is arranged between the first valve element of the first valve system and the body member, said cylinder communicating with the interior of the packer and with the exterior of the body member via separate communication bores in the wall of the body member, the communication between the cylinder and the exterior of the body member being controlled by an annular sleeve of the packer, and the com munication between the cylinder and the interior of the packer being controlled by a piston on the first valve element of the first valve system.

17. Means according to claim 1, wherein the annular sleeve forming part of the second valve system is movable between two end positions and cooperates with a first bore in the wall of the body member and forming a communication between the conduit through the body member and exterior of the body member, and with a second bore in the wall of the body member and forming a communication between the conduit through the body member and the interior of the inflatable packer, said annular sleeve closing off the first bore in one of the end positions and closing off the second bore in the other end position.

18. Means according to claim 17, wherein the second valve system includes fluid control means arranged in the conduit through the body member and actuatable by the first valve system, these fluid control means being displaceable between two end positions and closing off the second bore in one of the end positions.

19. Means according to claim 1. wherein the body member comprises a telescopic joint with torque transmission means, said first valve system comprises a first valve element connected via a connecting element to one of the elements of the telescopic joint and movable between two end positions, said first valve element closing off the passsage through the conduit extending through the body member in the extended position of the joint and leaving this passage free in the contracted position of the joint.

20. Means according to claim 19, wherein the first valve system comprises a second valve element being of the non-return type and displaceable between two end positions along the connector element, said second valve element closing off the passage through the said conduit in one of the end positions.

21. Method for controlling kicks during operations in a borehole penetrating subsurface formations, in which equipment including a drill string and a means as claimed in claim 1 is suspended, said method comprising the steps of:

a. stopping the operations;

b. closing off the annular space around the drill string at a level near the entrance of the borehole and actuating the first valve system to closing position;

c. pumping down fluid through the drill string to inflate the packer to close off the annular space around the drill string;

d. stopping the pumping fluid;

e. displacing the drill string with respect to the inflated packer set against the wall of the borehole, to operate the second valve system to open the communication between the exterior of the body member and the conduit extending through the body member; opening the annular space at the level near the borehole entrance;

g. resuming pumping of fluid through the drill string and changing the composition of this fluid;

h displacing fluid in the annular space by the fluid of different composition;

i. stopping the fluid circulation and subsequently displacing the drill string with respect to the inflated packer set against the wall of the borehole to oper ate the second valve system to close the communication between the conduit and the exterior of the body member to deflate the packer, and

j. resuming operations.

22. Method according to claim 21. wherein the step of lifting the drill string is included between the steps (a) and (b).

23. Method according to claim 21, in which the equipment includes the means as claimed in claim 8 in which the first valve system is actuated into closing po- 'sition in step (b) after closing off the annular space around the drill string at a level near the entrance of the borehole, by temporarily opening the upper end of the drill string and allowing an upward flow of fluid through the drill string.

24. Method according to claim 21, wherein the actuation of the first valve system in step (b) is performed by lifting the equipment free from the borehole.

25. Method according to claim 21, wherein the actuation of the first valve system in step (b) is performed by the step of closing the first valve element thereof by lifting the equipment free from the bottom of the borehole and by the step of closing the second valve element thereof by opening the upper end of the drill string and allowing an upward flow of fluid through the drill string, and to the step of closing off the annular space around the drill string at a level near the borehole entrance.

26. Method according to claim 21, in, and including between steps (e) and (f) the step of measuring the pressure in the annular space below the packer set against the bore-hole wall, said measuring step comprising slowly lowering the pressure within the upper suring step includes gradually varying the pressure at the entrance of the drill string and measuring the pressure at said entrance.

29. Method according to claim 28, wherein the annular space at the level near the borehole entrance is opened and the pressure at the entrance of the drill string is measured when there is change in conditions of the fluid in said-annular space. 

1. Means for controlling kicks during operations in a bore hole penetrating subsurface formations, said means being adapted to be included between two portions of tubular bore hole equipment and comprising: an elongated body member with a conduit longitudinally therethrough, and a first valve system arranged in this conduit for controlling the passage of fluid therethrough; an inflatable packer around the body member and comprising an elastic annular element connected at each end thereof to an annular sleeve arranged slidingly in axial direction on part of the outer wall of the elongate body member and sealing against the said outer wall; and a second valve system to control fluid communication between the exterior of the body member and the conduit extending longitudinally through the body member and between the interior of the inflatable packer and the said conduit through the body member, said second valve system including one of the annular sleeves, means being provided for retaining said sleeve during inflation of the packer when supplying fluid to the interior thereof in a position in which it closes off the communication between the exterior of the body member and the conduit through the body member but allows communication between this conduit and the interior of the inflatable packer.
 2. Means according to claim 1, wherein the annular sleeve forming part of the second valve system has a cross-section greater than the crosssection of the other annular sleeve, and is mounted on part of the body member having a smaller cross-section than the part on which the other annular sleeve is mounted.
 3. Means according to claim 1, wherein the annular sleeves of the packer are freely rotatable around the body member.
 4. Means according to claim 1, wherein the annular sleeve forming part of the second valve system is movable between two end positions and cooperates with at least one bore in the wall of the body member, which interior of the packer in the second and third position, and the other sleeve closing off the entrance to the bore leading from the exterior of the body member to the cylinder/piston system of the first valve element of the first valve system in the third position.
 5. Means according to claim 4, wherein the second valve system includes fluid control means arranged in the conduit through the body member and actuatable by the first valve system, these fluid control means being displaceable between two end positions and closing off the bore in one of the end positions.
 6. Means according to claIm 5, wherein a vent conduit is provided to vent the interior of the packer to the exterior of the body member in one of the end positions of the sleeve and of the fluid control means of the second valve system.
 7. Means according to claim 5, wherein the first valve system comprises a first valve element and a second valve element, each element being movable between two end positions, means adapted to urge the valve elements apart to positions in which there is a free passage through the conduit extending longitudinally through the elongated body member, and dampening means adapted to control the relative speed between the elements when they are urged apart, the two valve elements when contacting each other closing off the passage through the said conduit, the first valve element being a non-return valve and the second valve element being coupled to the fluid control means of the second valve system.
 8. Means according to claim 7, wherein the dampening means operate only when the valve elements of the first valve system are moved in the direction of the flow of drilling liquid when passing through the tubular borehole equipment.
 9. Means according to claim 7, wherein the dampening means is of the hydraulic type and arranged between the two valve elements of the first valve system.
 10. Means according to claim 7, wherein the dampening means is of the hydraulic type and arranged between the first valve element of the first valve system and the body member.
 11. Means according to claim 7, wherein a cylinder/piston system is arranged between the second valve element of the first valve system and the body member, said cylinder communicating with the exterior of the body member via a bore in the wall of the body member, which bore can be closed off by that annular sleeve of the inflatable packer, which sleeve does not form part of the second valve system.
 12. Means according to claim 7, wherein a cylinder/piston system is arranged between the first valve element of the first valve system and the body member, said cylinder communicating with the interior of the inflatable packer.
 13. Means according to claim 7, wherein a cylinder/piston system is arranged between the first valve element of the first valve system and the body member, said cylinder communicating with the exterior of the body member via a bore in the wall of the body member.
 14. Means according to claim 13, wherein the packer cooperates with the body member via a pin and slot system allowing the packer when inflated to be positioned in three distinct positions with respect to the body member, the annular sleeve forming part of the second valve system closing off the communication between the exterior of the body member and the conduit extending through the body member in the first position and second position, said sleeve closing off the communication between the said conduit and the bore in one end position of the sleeve forms a communication between the conduit through the body member and the exterior of the body member, and in the other end position of the sleeve forms a communication between the conduit through the body member and the interior of the inflatable packer.
 15. Means according to claim 7, wherein a cylinder/piston system is arranged between the first valve element of the first valve system and the body member, said cylinder communicating with the conduit extending axially through the body member via a bore, the entrance to which bore being controlled by the fluid control means of the second valve element that are arranged in the conduit.
 16. Means according to claim 15, wherein a second cylinder/piston system is arranged between the first valve element of the first valve system and the body member, said cylinder communicating with the interior of the packer and with the exterior of the body member via separate communication bores in the wall of the body member, the communication between the cylinder and the exterior of the body member being controlled by an annular Sleeve of the packer, and the communication between the cylinder and the interior of the packer being controlled by a piston on the first valve element of the first valve system.
 17. Means according to claim 1, wherein the annular sleeve forming part of the second valve system is movable between two end positions and cooperates with a first bore in the wall of the body member and forming a communication between the conduit through the body member and exterior of the body member, and with a second bore in the wall of the body member and forming a communication between the conduit through the body member and the interior of the inflatable packer, said annular sleeve closing off the first bore in one of the end positions and closing off the second bore in the other end position.
 18. Means according to claim 17, wherein the second valve system includes fluid control means arranged in the conduit through the body member and actuatable by the first valve system, these fluid control means being displaceable between two end positions and closing off the second bore in one of the end positions.
 19. Means according to claim 1, wherein the body member comprises a telescopic joint with torque transmission means, said first valve system comprises a first valve element connected via a connecting element to one of the elements of the telescopic joint and movable between two end positions, said first valve element closing off the passsage through the conduit extending through the body member in the extended position of the joint and leaving this passage free in the contracted position of the joint.
 20. Means according to claim 19, wherein the first valve system comprises a second valve element being of the non-return type and displaceable between two end positions along the connector element, said second valve element closing off the passage through the said conduit in one of the end positions.
 21. Method for controlling kicks during operations in a borehole penetrating subsurface formations, in which equipment including a drill string and a means as claimed in claim 1 is suspended, said method comprising the steps of: a. stopping the operations; b. closing off the annular space around the drill string at a level near the entrance of the borehole and actuating the first valve system to closing position; c. pumping down fluid through the drill string to inflate the packer to close off the annular space around the drill string; d. stopping the pumping fluid; e. displacing the drill string with respect to the inflated packer set against the wall of the borehole, to operate the second valve system to open the communication between the exterior of the body member and the conduit extending through the body member; f. opening the annular space at the level near the borehole entrance; g. resuming pumping of fluid through the drill string and changing the composition of this fluid; h. displacing fluid in the annular space by the fluid of different composition; i. stopping the fluid circulation and subsequently displacing the drill string with respect to the inflated packer set against the wall of the borehole to operate the second valve system to close the communication between the conduit and the exterior of the body member to deflate the packer, and j. resuming operations.
 22. Method according to claim 21, wherein the step of lifting the drill string is included between the steps (a) and (b).
 23. Method according to claim 21, in which the equipment includes the means as claimed in claim 8 in which the first valve system is actuated into closing position in step (b) after closing off the annular space around the drill string at a level near the entrance of the borehole, by temporarily opening the upper end of the drill string and allowing an upward flow of fluid through the drill string.
 24. Method according to claim 21, wherein the actuation of the first valve system in step (b) is performed by lifting the equiPment free from the borehole.
 25. Method according to claim 21, wherein the actuation of the first valve system in step (b) is performed by the step of closing the first valve element thereof by lifting the equipment free from the bottom of the borehole and by the step of closing the second valve element thereof by opening the upper end of the drill string and allowing an upward flow of fluid through the drill string, and to the step of closing off the annular space around the drill string at a level near the borehole entrance.
 26. Method according to claim 21, in, and including between steps (e) and (f) the step of measuring the pressure in the annular space below the packer set against the bore-hole wall, said measuring step comprising slowly lowering the pressure within the upper end of the drill string to open the first valve system, measuring the pressure variation in the string until the lowest value has been reached, followed by opening the upper end of the drill string to close the first valve system.
 27. Method according to claim 21, including the step of measuring the pressure in the annular space below the packer set against the wall of the borehole, this step being carried out between the steps e) and f).
 28. Method according to claim 27, in which the measuring step includes gradually varying the pressure at the entrance of the drill string and measuring the pressure at said entrance.
 29. Method according to claim 28, wherein the annular space at the level near the borehole entrance is opened and the pressure at the entrance of the drill string is measured when there is change in conditions of the fluid in said annular space. 